Subsequent Events - Additional Information (Detail)	12 Months Ended	1 Months Ended
Dec. 31, 2012	Jan. 01, 2013 Subsequent Event [Member]
Subsequent Event [Line Items]
Percentage of management fee reduction		0.125%
Percentage of management fee paid to the Advisor	2.00%	1.50%

Management Fees Based On Assets Under Management Percentage

No definition available.

Name:	acef_ManagementFeesBasedOnAssetsUnderManagementPercentage
Namespace Prefix:	acef_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration